Elenco Electronics AM/FM-108K Instruction Manual

AM/FM RADIO KITMODEL AM/FM-108KINTEGRAL CIRCUIT, 9 TRANSISTORS, 4 DIODESElencoTMElectronics, Inc.Copyright © 2003, 1989 by ElencoTMElectronics, Inc. A

-9-OUTPUT BIAS TESTPut the battery into the holder.STATIC MEASUREMENTSPOWER TESTTP15COMVVFor all measurements, connect your equipment GNDto circuit GN

DYNAMIC MEASUREMENTSGAIN-10-Figure 8TP15COMVVTP15HzGeneratorIf you do not have an audio generator, skip the following test and go directly to Section

-11-Figure 9AC BANDWIDTHConnect the oscilloscope and audio generator toyour circuit as shown in Figure 9. Set the audiogenerator for a frequency of 1k

MAXIMUM POWER OUTPUTThe maximum power output before distortion due to“clipping” can be calculated using the voltage Vclpobtained in the Distortion Ste

-13-Vp = Vclp/2 Vp = ______Vrms = Vp x .7 Vrms = ______Max power out = (Vrms)2/8 Max power out = ______Since the battery power equals the battery volt

SECTION 2AM DETECTOR AND AGC STAGE-14-Figure 12SwitchJ2 - Jumper Wire(use lytic lead)The purpose of the automatic gain control (AGC)circuit is to main

STATIC MEASUREMENTSAGC ZERO SIGNAL BIASWith the power turned OFF, connect your VOM to TP5 as shown in Figure 13. Make sure that the AM/FM switchis in

DYNAMIC MEASUREMENTSAM DETECTOR AND AGC TESTConnect your VOM and RF generator as shown in Figure 14.-16-Figure 15TP15GENERATORHzTP15.001mFIf your RF g

SECTION 3-17-AM DETECTOR BANDWIDTH TESTFigure 16kHzkHzkHzConnect your test equipment as shown in Figure 15.Set the generator at 455kHz with 80% modula

-18-ASSEMBLY INSTRUCTIONSSTATIC MEASUREMENTSQ9 BIASFigure 17T7 - AM IF Coil(White Dot)TP4 - Test Point Pin(see Figure A)R40 - 10kW Resistor(brown-blac

The AM/FM Radio project is divided into two parts, the AM Radio Section and the FM Radio Section. At this time, onlyidentify the parts that you will n

-19-DYNAMIC MEASUREMENTSAC GAINConnect your test equipment as shown in Figure 18.Figure 18TP15GENERATORHzTP15.001mFSet the generator at 455kHz, no mod

-20-SECTION 4FIRST AM IF AMPLIFIERQ8 BASE BIASConnect your VOM to the circuit as shown in Figure 13.Set your VOM to read 2 volts DC and turn the power

-21-DYNAMIC MEASUREMENTSAC GAINConnect your test equipment as shown in Figure 19.The scope probe must have an input capacitance of12pF or less, otherw

-22-The “difference frequency” is used as theintermediate frequency in AM radios. The collector ofQ7 also contains an IF transformer (T6) tuned only t

-23-It is important to know which of the two types of the tuning gang capacitor you have received with your kit. Look at thegang capacitor that you ha

-24-Figure MFasten the knob to the shaft of thecapacitor with a screw.Rotate the knob fully clockwise.Peel off the protective backing onthe label. Lin

STATIC MEASUREMENTSQ7 BIASConnect your VOM to the circuit as shown in Figure 20.-25-Figure 21Figure 20TP15VCOM VTP15Connect a clip lead from TP6 to th

-26-AM FINAL ALIGNMENTSThere are two different AM alignment procedures.The first alignment procedure is for those who do nothave test equipment and th

AM ALIGNMENT WITH TEST EQUIPMENTIF ALIGNMENT-27-.001mFGENERATORHzTP15Tune the radio for a station around 600kHz. With the“magic wand” place the brass

-28-Set the RF generator at 455kHz, modulation of400Hz 80% and minimum voltage out. Set theoscilloscope to read .1 volts per division and turn thepowe

-2-IDENTIFYING RESISTOR VALUESUse the following information as a guide in properly identifying the value of resistors.IDENTIFYING CAPACITOR VALUESCapa

-29-Set the generator at 600kHz, 400Hz 80%modulation, moderate signal strength. Set theoscilloscope to read .1 volts per division. Turn thetuning knob

-30-QUIZ - AM SECTIONINSTRUCTIONS: Complete the following examination, check your answers carefully.Answers: 1. D, 2. D, 3. A, 4. A, 5. C, 6. A, 7. D,

-31-PARTS LIST FOR FM SECTIONRESISTORSQty. Symbol Value Color Code Part #2 R9, 23 100W 5% 1/4W brown-black-brown-gold 1310001 R25 220W 5% 1/4W red-red

SECTION 6THE FM RADIOFigure 26mF.01mFmFIn the AM DETECTOR section we observed that theaudio was detected from changes in the amplitude ofthe incoming

Test Point Pin-33-ASSEMBLY INSTRUCTIONSTest Point PinFoil Sideof PC BoardFigure ALytic CapacitorFigure BBe sure that the negative lead is inthe correc

STATIC MEASUREMENTS-34-Figure 29TP15COMVVTP15VCOM VBatteryFigure 28Connect your VOM to the circuit as shown in Figure 29.Turn the power ON. The voltag

DYNAMIC MEASUREMENTSAC GAIN-35-TP15TP15.001mFGeneratorGenerator.001mFFigure 31HzHzTP15If you don’t have an RF generator and oscilloscope, skip to Sect

-36-SECTION 7Figure 3310.625MHz10.775MHz10.7MHz.707METHOD #2ALIGNMENT OF RATIO DETECTOR USING ARF GENERATOR AND OSCILLOSCOPEConnect the RF generator a

-37-ASSEMBLY INSTRUCTIONSSTATIC TESTSQ5 BIASFigure 34TP10 - Test Point Pin(see Figure A)T2 - FM IF Coil(Green Dot)C17 - .01mF Discap (103)R16 - 10kW R

-38-AC GAINConnect the RF generator and oscilloscope to thecircuit as shown in Figure 35. The scope probe musthave an input capacitance of 12pF or les

Section 9-3-FM RFAMPLIFIERFMOSCILLATOR1ST FM IFAMPLIFIERAFCFigure 1Section 8Section 7 Section 6Section 1Section 5 Section 4Section 3 Section 2FM MIXER

-39-SECTION 8FIRST FM IF AMPLIFIERSTATIC TESTSConnect your VOM as shown in Figure 36. Turn thepower ON. The voltage at the base of Q4 shouldapproximat

-40-Figure 37GENERATORHzTP15.001mFTP15Connect the RF generator and oscilloscope andoscilloscope to the circuit as shown in Figure 37. Thescope probe m

-41-SECTION 9FM RF AMPLIFIER, MIXER, OSCILLATOR, AND AFC STAGER10 - 10kW Resistor(brown-black-orange-gold)C12 - .005mF Discap (502)R8 - 22kW Resistor(

-42-STATIC MEASUREMENTSFigure 38Q3 BIASTP15VCOM VWith the power turned OFF, connect your VOM to thecircuit as shown in Figure 38. Set your VOM to read

-43-BANDWIDTH TESTFigure 39C7 - .001mF Discap (102)R4 - 33kW Resistor(orange-orange-orange-gold)Q2 - 2N3904 Transistor(see Figure C)R5 - 33kW Resistor

-44-STATIC MEASUREMENTSFigure 40R30 - 390kW Resistor(orange-white-yellow-gold)D1 - Varactor Diode(see Figure D)C27 - .001mF Discap (102)R29 - 390kW Re

Connect the RF generator and VOM to the circuit asshown in Figure 41. Set your VOM to read 9 voltsDC. Set your generator at 10.7MHz no modulationand m

Q1 BIASConnect your VOM to the circuit as shown inFigure 42. Set your VOM to read 9 volts andturn the power ON. The voltage at the baseof Q1 should be

With an alignment tool or screwdriver turn coils T1,T2 and T3 fully counter-clockwise. DO NOT FORCETHE COILS ANY FURTHER. Turn each coil in about1 1/4

is heard. Place the iron end of the “magic wand” nearL3. If the station is heard, it means that L3 needsless capacitance. Carefully adjust the FM osci

-4-IntroductionThe most important factor in assembling your Superhet 108 AM/FM Radio Kit is good soldering techniques.Using the proper soldering iron

-49-OSCILLATOR ALIGNMENTRemove the clip lead and set your generator at88MHz modulator at 1kHz, 22.5kHz deviation andminimum voltage output. Tune the r

-50-DC VOLTAGESThe voltage readings below should be used in troubleshooting the FM section. (Switch at FM position.)Q1 B 1.6 Q4 B 1.3E .9 E .7C 7.0 C

-51-QUIZ - FM SECTIONINSTRUCTIONS: Complete the following examination, check your answers carefully.Answers: 1. C, 2. B, 3. A, 4. A, 5. A, 6. B, 7. C,

-52-2. Bend the four flaps upward as shown.1. Start at one edge and carefully remove thebaffle from the bottom the kit box.brownsideAM/FM-108K Kit Car

-53-3. Bend the top side upward as shown.4. Bend the two sides upward. Attach thethree sides using scotch tape or glue(Elmer’s, Duco Cement, or other)

-54-SCHEMATIC DIAGRAM - AM/FM RADIO

ElencoTMElectronics, Inc.150 W. Carpenter AvenueWheeling, IL 60090(847) 541-3800http://www.elenco.come-mail: [email protected]

-5-SEMICONDUCTOR PARTS FAMILIARIZATIONThis section will familiarize you with the proper method used to test the transistors and the diode.TRANSISTOR T

-6-SECTION 1AUDIO AMPLIFIERFigure 3The purpose of the Audio Amplifier is to increase theaudio power to a level sufficient to drive an 8 ohm speaker.To

DiodeBe sure that the band isin the correct direction.Test Point PinASSEMBLY INSTRUCTIONSWe will begin by installing resistor R43. Identify the resist

-8-ASSEMBLY INSTRUCTIONSFigure FKnobNutWasherCut offlocating pinSolder all 5 tabs to PC boardPlastic WasherFigure HMount the jack with the nut from th